The Sivalik Hills, also known as the Shivalik Hills and Churia Hills, are a
mountain range of the outer
Himalayas that stretches over about 2,400 km (1,500 mi) from the
Indus River eastwards close to the
Brahmaputra River, spanning the northern parts of the
Indian subcontinent. It is 10–50 km (6.2–31.1 mi) wide with an average elevation of 1,500–2,000 m (4,900–6,600 ft). Between the
Teesta and
Raidāk Rivers in
Assam is a gap of about 90 km (56 mi).[1] The
literal translation of "Sivalik" is 'tresses of
Shiva'.[2] Sivalik region is home to the
Soanian archaeological culture.[3] The hills are well known for their
Neogene and
Pleistocene aged vertebrate fossils.[4]
Geology
Geologically, the Sivalik Hills belong to the
Tertiarydeposits of the outer Himalayas.[5] They are chiefly composed of
sandstone and
conglomerate rock formations, which are the solidified
detritus of the Himalayas[5] to their north; they are poorly consolidated. The sedimentary rocks comprising the hills are believed to be 16–5.2 million years old.[6]
They are bounded on the south by a fault system called the Main Frontal Thrust, with steeper slopes on that side. Below this, the coarse alluvial
Bhabar zone makes the transition to the nearly level plains. Rainfall, especially during the summer
monsoon, percolates into the Bhabar, then is forced to the surface by finer alluvial layers below it in a zone of springs and marshes along the northern edge of the
Terai or plains.[7]
Prehistory
Ganges River cutting through the Sivalik Hills
View of the Sivalik Hills from Sukhna Lake at dawn
Winter morning in Terai
The Sivalik Hills are well known for fossils of vertebrates, spanning from the Early
Miocene, until the
Middle Pleistocene, around 18 million to 600,000 years ago.[8][9]
Remains of the
Lower PaleolithicSoanian culture dating to around 500,000 to 125,000 BP were found in the Sivalik region.[10] Contemporary to the
Acheulean, the Soanian culture is named after the
Soan Valley in the Sivalik Hills of
Pakistan. The Soanian archaeological culture is found across Sivalik region in present-day India, Nepal and Pakistan.[3]
Sivapithecus (a kind of
ape, formerly known as Ramapithecus) is among many
fossil finds in the Sivalik region.[11]
A number of fossil
ratites were reported from the Sivalik Hills, including the extinct
Asian ostrich, Dromaius sivalensis and Hypselornis. However, the latter two species were named only from toe bones that have since been identified as belonging to an
ungulate mammal and a
crocodilian, respectively.[12]
Demographics
The low human population density in the Sivalik Hills and along the steep southern slopes of the
Lower Himalayan Range created a cultural, linguistic, and political buffer zone between populations in the
plains to the south and the hills beyond the Mahabharat escarpment, enabling different evolutionary paths with respect to language and culture.[citation needed]
^Lycett, S. J. (2007). "Is the Soanian techno-complex a Mode 1 or Mode 3 phenomenon? A morphometric assessment". Journal of Archaeological Science. 34 (9): 1434–1440.
doi:
10.1016/j.jas.2006.11.001.